/*
 * ungzip.h
 * --------
 * Purpose: Header file for .gz loader
 * Notes  : (currently none)
 * Authors: OpenMPT Devs
 * The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
 */

#pragma once

#include "openmpt/all/BuildSettings.hpp"
#include "openmpt/base/Endian.hpp"

#include "archive.h"

OPENMPT_NAMESPACE_BEGIN

#if defined(MPT_WITH_ZLIB) || defined(MPT_WITH_MINIZ)

class CGzipArchive : public ArchiveBase
{
public:
	struct GZheader
	{
		uint8le magic1;  // 0x1F
		uint8le magic2;  // 0x8B
		uint8le method;  // 0-7 = reserved, 8 = deflate
		uint8le flags;   // See GZ_F* constants
		uint32le mtime;  // UNIX time
		uint8le xflags;  // Available for use by specific compression methods. We ignore this.
		uint8le os;      // Which OS was used to compress the file? We also ignore this.
	};

	struct GZtrailer
	{
		uint32le crc32_;  // CRC32 of decompressed data
		uint32le isize;   // Size of decompressed data modulo 2^32
	};

protected:
	enum MagicBytes
	{
		GZ_HMAGIC1   = 0x1F,
		GZ_HMAGIC2   = 0x8B,
		GZ_HMDEFLATE = 0x08,
	};

	enum HeaderFlags
	{
		GZ_FTEXT     = 0x01,  // File is probably ASCII text (who cares)
		GZ_FHCRC     = 0x02,  // CRC16 present
		GZ_FEXTRA    = 0x04,  // Extra fields present
		GZ_FNAME     = 0x08,  // Original filename present
		GZ_FCOMMENT  = 0x10,  // Comment is present
		GZ_FRESERVED = (~(GZ_FTEXT | GZ_FHCRC | GZ_FEXTRA | GZ_FNAME | GZ_FCOMMENT))
	};

	GZheader header;

public:

	bool ExtractFile(std::size_t index) override;

	CGzipArchive(const FileReader &file);
	~CGzipArchive() override;
};

MPT_BINARY_STRUCT(CGzipArchive::GZheader, 10)
MPT_BINARY_STRUCT(CGzipArchive::GZtrailer, 8)

#endif // MPT_WITH_ZLIB || MPT_WITH_MINIZ

OPENMPT_NAMESPACE_END
